Shortness of Breath While Lying Down: a Woman with Orthopneic Asthma

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CMAJ Practice

What is your call? Shortness of breath while lying down: a woman with orthopneic asthma

Chou-Han Lin, Mong-Wei Lin, Jin-Shing Chen, Chong-Jen Yu

See related practice article by Lee and Cheng, page 80

Competing interests: None 36-year-old woman with a six-month second of expiration (FEV1) of 17.5% of pre- history of worsening shortness of dicted, a forced vital capacity (FVC) of 75.7% declared.

breath was admitted to hospital for and an FEV1/FVC ratio of 20.4% of predicted. This article has been peer A reviewed. investigation. She had received a diagnosis of Her flow–volume loop showed slowing and bronchial asthma six months earlier, for which flattening in the expiratory limb (Figure 1), Correspondence to: treatment with steroids and bronchodilators had which led us to re-examine her chest radiograph Dr. Chong-Jen Yu, [email protected] been ineffective. Her history included allergic taken on admission (Figure 2). The tracheal air rhinitis and an eight pack-year history of smok- column was not deviated, and no conspicuous CMAJ 2011. DOI:10.1503 ing, which she had stopped since her diagnosis lesions were noted. /cmaj.081801 of asthma. On admission, the patient was in mild respi- What is your diagnosis? ratory distress. She had a temperature of 36.5°C, a pulse rate of 90 beats/min, a respira- a. Upper airway obstruction tory rate of 22 breaths/min and a blood pressure b. Left-sided heart failure (cardiac asthma) of 116/64 mm Hg. She had diffuse wheezing on c. Status asthmaticus expiration and during the first half of inspira- d. Hepatopulmonary syndrome tion. We noticed that she had orthopnea and e. Exacerbation of chronic obstructive pulmon - had to use three pillows for relief. She had not ary disease mentioned this symptom to her treating physi- cians. Her distress when lying down occurred even though her oxygen saturation remained above 98% on 2 L of oxygen per minute via nasal cannula. A pulmonary function test showed a forced expiratory volume in the first

2 Expiratory flow, L/s Expiratory flow, 0 1 2345 2 Volume, L 4

Inspiratory flow, L/s Inspiratory flow, 10

Figure 1: Flow–volume loop from a 36-year-old Figure 2: Posteroanterior chest radiograph, show- woman with orthopnea, showing a plateau phase ing a straight tracheal air column (arrow) without on the expiratory arm. narrowing or deviation.

Practice

What is your next step? Discussion

a. Give magnesium sulfate along with standard Orthopnea is often associated with congestive combination of oxygen, bronchodilators and heart failure, chronic obstructive pulmonary dis- steroids ease, anterior mediastinal tumours and diaphrag- b. Give antibiotics along with standard combina- matic weakness. Tracheal tumours, as in our tion of oxygen, bronchodilators and steroids patient, are a rare cause of orthopnea.1 Because c. Order a lateral chest radiograph and a com- our patient’s tumour stalk emerged from the ante- puted tomography (CT) scan of the chest rior tracheal wall, part of the tumour approached d. Arrange contrast echocardiography the opposing membranous portion and occluded e. Administer intravenous nitroglycerin with an the lumen when she lay down (Figure 4). angiotensin-converting-enzyme inhibitor The posteroanterior chest radiograph is an appropriate initial imaging study for assessing The diagnosis is (a) upper airway obstruction, dyspnea. However, it is a relatively poor tool for and the next step is (c) order a lateral chest radio - identifying tumours situated distally in the ante- graph and a CT scan. We made the diagnosis rior or posterior tracheal wall. A lateral chest with the help of the flow–volume loop, which radio graph is helpful for assessing tracheal was consistent with intrathoracic upper airway tumours in these locations. Most pleomorphic obstruction. Her lateral chest radiograph showed adenomas are located in the upper third of the tra- a tumour-like opacity in the trachea (Figure 3). chea.2 However, the intrathoracic location of our The CT scan showed a tracheal tumour with patient’s tumour lowered its visibility on the almost total obstruction of the tracheal lumen postero anterior view of the chest radiograph. A (Figure 4). Bronchoscopy showed a whitish lateral view provides better exposure, without bosselated tumour arising from the anterior wall interference from the thoracic spine and sternum.3 of the trachea 6 cm below the vocal cords. Computed tomography is useful in detecting The patient underwent segmental resection of and assessing tracheal tumours, given that not all the trachea with anastomosis. A whitish elastic soft-tissue lesions are visible on chest radiogra- tumour (2 × 2 × 2 cm) was found 3 cm above the phy. As in our case, pulmonary function testing carina, extending from the anterior tracheal wall can be helpful in diagnosing tracheal lesions, with (Figure 5). Histopathology results were consistent confirmation provided by direct visualization with a pleomorphic adenoma. After resection, her using bronchoscopy. wheezing and orthopnea disappeared. Differential diagnosis Orthopnea occurs most frequently in patients with heart failure. These patients find relief in an upright position because this posture reduces the demand on their pulmonary circulation. A con- stellation of clinical symptoms and signs such as paroxysmal nocturnal dyspnea, distention of the veins in the neck and lung crackles can also be found in patients with heart failure. The subacute course and lack of these features in our patient ruled out this disease as a cause of her orthopnea.

Figure 3: Lateral chest radiograph, showing an Figure 4: Chest computed tomography scan, show- opacity (arrow) arising from the anterior tracheal ing a pedunculated tumour (arrow) nearly obliter- wall with a patent posterior tracheal lumen. ating the tracheal lumen.

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Practice

Small airway obstruction Upper airway obstruction Variable Variable COPD Asthma attack intrathoracic extrathoracic Fixed FVC N to N NN

FEV1 N

FEV1/FVC N to N

Flow–volume loop

Figure 6: Typical findings of pulmonary function tests in patients with small (lower) airway and upper airway obstruction. COPD = chronic obstructive pul-

monary disease, FVC = forced vital capacity, FEV1 = forced expiratory volume in Figure 5: Tracheal tumour attached to the anterior the first second of expiration. Reprinted, with permission, from Hyatt et al.4 of the tracheal ring. Copyright © 2009 Lippincott Williams & Wilkins (http://lww.com).

Also, her chest radiograph did not show car- diagnosing upper airway obstruction.5 For this diomegaly or pulmonary edema, which are often condition, the ratio of maximal expiratory to associated with heart failure. maximal inspiratory flow at 50% of vital capac-

Hepatopulmonary syndrome develops in the ity (MEF50:MIF50 ratio) is more useful. The

setting of chronic liver disease. The resulting MEF50:MIF50 ratio, normally between 0.9 and dilated pulmonary capillaries create intrapul- 1.0, will decrease to less than 0.2 in patients with monary shunts. Patients with this condition often an intrathoracic obstruction or increase to more exhibit platypnea (shortness of breath relieved than 1.0 in those with an extrathoracic obstruc- with lying down) or orthodeoxia (deoxygenation tion.6 As shown in Figure 6, direct inspection of in the sitting or standing position) rather than the flow–volume loop is helpful when interpret- orthopnea. ing spirometric data and can be used along with Occasionally, orthopnea is also found in specific flow calculations to make the diagnosis patients with chronic obstructive lung disease of upper airway obstruction.6 and asthma, since the upright position may be associated with reduced pooling of lung secre- References tions and improved diaphragmatic excursion. 1. Gaissert HA, Grillo HC, Shadmehr B, et al. Uncommon primary Orthopnea tends to be a late manifestation of tracheal tumors. Ann Thorac Surg 2006;82:268-73. 2. Aribas OK, Kanat F, Avunduk MC. Pleomorphic adenoma of chronic lung disease. Wheezing is commonly the trachea mimicking bronchial asthma: report of a case. Surg observed in chronic obstructive pulmonary dis- Today 2007;37:493-5. 3. Li W, Ellerbroek NA, Libshitz HI. Primary malignant tumors of ease and asthma, and subacute or chronic upper the trachea; a radiologic and clinical study. Cancer 1990;66: 894-9. airway obstruction can mimic diseases of periph- 4. Hyatt RE, Scanlon PD, Nakamura M. Interpretation of pulmonary function tests: a practical guide. 3rd ed. Philadelphia: eral airflow obstruction. Our patient’s wheezing Lippincott Williams & Wilkins; 2009. Figure 2-7. pattern, however, which extended from expira- 5. Miller RD, Hyatt RE. Obstructing lesions of the larynx and tra- tion to inspiration, would be unusual in these chea: clinical and physiologic characteristics. Mayo Clin Proc 1969;44:145-61. conditions. 6. Lunn WW, Sheller JR. Flow volume loops in the evaluation of upper airway obstruction. Otolaryngol Clin North Am 1995;28: 721-9. Pulmonary function testing Not only is spirometry a diagnostic tool for Affiliations: From the Division of Chest Medicine, Depart- chronic obstructive lung disease and asthma, it ment of Internal Medicine (C.-H. Lin), Far Eastern Memorial can also help identify upper airway obstruction Hospital, Taipei, Taiwan; the Division of Thoracic Surgery, 4 Department of Surgery (M.-W. Lin, Chen), National Taiwan (Figure 6). FEV1, the spirometric parameter University Hospital, Taipei, Taiwan; and the Division of used for assessing chronic obstructive pul- Chest Medicine, Department of Internal Medicine (Yu), monary disease and asthma, is less sensitive in National Taiwan University Hospital, Taipei, Taiwan

CMAJ, January 11, 2011, 183(1) 79